support for per package (per arch) timeout increase

Some package just take longer to test than the standard timeout. Currently we'd block those, but ideally if the test is sane, we'd want to allow for some more time.

At the moment, I'm looking at statsmodels in the python3-defaults transition, and it's just slow on armel (because the lack of hardware support for floating points), which isn't an issue for one supported Python version, but trips the timeout in periods where two Python versions are supported.